单向拉伸碳纤维填充导电橡胶薄膜的裂纹扩展行为

Crack Propagation Behavior of Carbon Fiber-Filled Conductive Rubber Films Under Uniaxial Tension

为研究单向拉伸应力条件下裂纹对导电橡胶薄膜的影响,采取喷涂法制备碳纤维填充的导电橡胶薄膜,用撕裂能评价含预制裂纹橡胶薄膜的抗裂纹扩展能力,探究含不同长度、角度、位置和形状的预制裂纹导电橡胶薄膜的力学行为,并分析碳纤维对裂纹扩展的影响。结果表明,随表面I型裂纹长度增加,导电橡胶薄膜的拉伸强度和断裂伸长率呈近线性下降,而其撕裂能则分段下降;内部裂纹对薄膜性能影响稍大于表面裂纹,裂纹形状对薄膜的拉伸性能的影响更为明显;随I型裂纹与应力夹角的增大,薄膜拉伸性能不断降低,当裂纹与外力垂直时,其抗力最低;薄膜预制裂纹受力扩展过程中伴随二次裂纹的产生,二次裂纹对裂纹扩展有一定的阻碍作用,同时碳纤维因改变裂纹的扩展方向而阻碍了裂纹的扩展。

In order to investigate the effect of crack on tensile property of conductive rubber films(CRFs) under uniaxial tension load condition, carbon fiber-filled silicon rubber films were fabricated by spraying process, and tensile properties in cluding tensile strength, elongation at break and tearing energy were tested to evaluate the crack propagation resistance of CRFs with precracks in different shape, size and directions. Fractograph was conducted to analyze the effect of carbon fibers on crack propagation in CRFs. Results show that the tensile strength and elongation at break of precracked CRFs decrease approximately linearly with the increasing length of surface crack in mode I, while the tearing energy decreases by stages. Meanwhile, crack shape exhibits more important influence on the tensile properties than crack location does as well as that greater adverse influence on tensile properties of CRFs comes from centered cracks seems greater compared to that from surface crack. With the increase of angle between crack plane and stress in centered-crack mode I, tensile properties of precracked CRFs decrease till the lowest resistance appears when the crack plane is perpendicular to the stress. Secondary cracks appear in crack propagation, which become as obstacle to the crack propagation. Carbon fibers play the same hindrance role by means of reinforcing the CRFs as well as changing the propagation direction of the crack.